In recent months, the name Harry Macklowe has become synonymous with the roiling fortunes of New York City's high-stakes real estate market. Now that those fortunes have turned sour, a different Macklowe—his son William—is stepping forward to take over.

At the peak of the market last year, Macklowe senior, 71, shelled out a record $7 billion to buy seven Manhattan office buildings from Blackstone Group, risking a real estate empire that included the prized General Motors Building. 

In one fell swoop, Macklowe's audacity doubled his holdings to 12 million square feet of commercial office space spread out over 13 skyscrapers, and it allowed father and son to practically set the prices in the elite commercial corridor of New York City real estate that is home to the largest concentration of hedge funds in the world.

But when the credit markets froze, Macklowe found himself unable to refinance billions in bridge loans that came due in February, forcing him to put the G.M. Building, and a number of other buildings, up for sale to avoid financial ruin.

Now with a deal to sell the trophy tower to a group led by Mort Zuckerman of Boston Properties for $2.9 billion, it's William Macklowe, 40, who has stepped into the spotlight. The longtime president of Macklowe Properties announced his father would step down as chairman in the coming weeks and he would take the reins.

In many respects, the elder Macklowe has already begun to fade. It's been William who has explained the deal in interviews to the New York Times and Wall Street Journal—though he is done speaking with the press and "wants the media frenzy to be at an end so he can rebuild his company," a spokesman said today.

Associates of the Macklowes say that William played a key role in negotiating the sale of the G.M. Building, which made it only more apparent that "Bill has come into his own."

"I think it's time for a generational shift," says Jonathan Mechanic, chairman of the real estate department at the law firm of Fried Frank, and one of the attorneys who helped the Macklowes hash out the G.M. sale. "Bill has been president for some time, and it's the next chapter for this company which has been a major player in New York and will continue to be a major player in New York."

Though the Macklowes reportedly put up just $50 million of their own money and borrowed the balance to buy the E.O.P. properties, it was Harry Macklowe's decision to take out a $1.2 billion bridge equity loan from the Fortress Investment Group that most imperiled his family dynasty.

As collateral, Macklowe offered the G.M. Building and a "personal recourse" loan that put his personal assets at risk in the case of default. The younger Macklowe told the Wall Street Journal he was strongly opposed to the deal, and began pushing almost immediately to try and reduce their risk.

"You should always be opposed to recourse," he said.

When the credit markets froze and the Macklowes defaulted in February, it was the younger Macklowe who hashed out a deal with Fortress that allowed for a partial payment—with the proceeds from a building—and a crucial four-month extension, Mechanic says.

"He played a key role in getting the extension, persuading people that we had the wherewithal to affect this kind of transaction, and we needed the requisite time to do it," Mechanic says. "Consequently we were able to make a deal with the lending group and with Boston Properties." Going forward, William Macklowe is likely to bring a more cautious approach to the business than his father, "having had the experience of the ups and downs," Mechanic says.

Barry Hersh, associate professor at N.Y.U. Real Estate Institute, describes the older Macklowe as  "an old-line kind of a swashbuckler who liked pushing the limits."

The younger Macklowe, Hersh says, "seems to be less anxious to push it to the ultimate limits. That's fairly clear."

But there's little question Macklowe's style will continue to be shaped by that of his father, who made a name for himself by coming up with innovative ways to develop properties and increase their value.

After attending New York University, William Macklowe worked as appraisal analyst in the real estate finance department of Manufacturers Hanover Trust Company, and according to some reports, did a stint in banking at Salomon Brothers.

He went to work for his father in his mid-20s, where he  "learned from one of the most talented real estate professionals in our time."

"He has all the genius and the vision the Macklowe hereditary traits, and is perhaps a little more cautious having had the experience of the ups and down."

He's also "got a good sense of humor," Mechanic says. 

"That's very helpful sometimes when you're in a tense situation, to lighten the mood," he says. "Obviously we've just come through one."